Multi-Electrode Catheter Assemblies for Renal Neuromodulation and Associated Systems and Methods

ABSTRACT

Catheter apparatuses, systems, and methods for achieving renal neuromodulation by intravascular access are disclosed herein. One aspect of the present technology, for example, is directed to a treatment device having a multi-electrode array configured to be delivered to a renal blood vessel. The array is selectively transformable between a delivery or low-profile state (e.g., a generally straight shape) and a deployed state (e.g., a radially expanded, generally spiral/helical shape). The multi-electrode array is sized and shaped so that the electrodes or energy delivery elements contact an interior wall of the renal blood vessel when the array is in the deployed (e.g., spiral/helical) state. The electrodes or energy delivery elements are configured for direct and/or indirect application of thermal and/or electrical energy to heat or otherwise electrically modulate neural fibers that contribute to renal function.

CROSS REFERENCE TO RELATED APPLICATION(S)

The present application claims the benefit of and priority U.S. patentapplication Ser. No. 13/793,647 filed Mar. 11, 2013, now allowed, whichclaims the benefit of and priority to U.S. Provisional PatentApplication No. 61/646,218, filed May 11, 2012, both of which areincorporated herein by reference in their entirety.

ADDITIONAL APPLICATIONS INCORPORATED BY REFERENCE

The following applications are also incorporated herein by reference intheir entireties:

U.S. patent application Ser. No. 13/281,360, filed Oct. 25, 2011;

U.S. patent application Ser. No. 13/281,361, filed Oct. 25, 2011; and

U.S. patent application Ser. No. 13/281,395, filed Oct. 25, 2011.

As such, components and features of embodiments disclosed in theseapplications may be combined with various components and featuresdisclosed in the present application.

TECHNICAL FIELD

The present technology relates generally to renal neuromodulation andassociated systems and methods. In particular, several embodiments aredirected to multi-electrode radio frequency (RF) ablation catheterassemblies for intravascular renal neuromodulation and associatedsystems and methods.

BACKGROUND

The sympathetic nervous system (SNS) is a primarily involuntary bodilycontrol system typically associated with stress responses. Fibers of theSNS innervate tissue in almost every organ system of the human body andcan affect characteristics such as pupil diameter, gut motility, andurinary output. Such regulation can have adaptive utility in maintaininghomeostasis or preparing the body for rapid response to environmentalfactors. Chronic activation of the SNS, however, is a common maladaptiveresponse that can drive the progression of many disease states.Excessive activation of the renal SNS in particular has been identifiedexperimentally and in humans as a likely contributor to the complexpathophysiology of hypertension, states of volume overload (such asheart failure), and progressive renal disease. For example, radiotracerdilution has demonstrated increased renal norepinephrine (“NE”)spillover rates in patients with essential hypertension.

Cardio-renal sympathetic nerve hyperactivity can be particularlypronounced in patients with heart failure. For example, an exaggeratedNE overflow from the heart and kidneys of plasma is often found in thesepatients. Heightened SNS activation commonly characterizes both chronicand end stage renal disease. In patients with end stage renal disease,NE plasma levels above the median have been demonstrated to bepredictive of cardiovascular diseases and several causes of death. Thisis also true for patients suffering from diabetic or contrastnephropathy. Evidence suggests that sensory afferent signals originatingfrom diseased kidneys are major contributors to initiating andsustaining elevated central sympathetic outflow.

Sympathetic nerves innervating the kidneys terminate in the bloodvessels, the juxtaglomerular apparatus, and the renal tubules.Stimulation of the renal sympathetic nerves can cause increased reninrelease, increased sodium (Na+) reabsorption, and a reduction of renalblood flow. These neural regulation components of renal function areconsiderably stimulated in disease states characterized by heightenedsympathetic tone and likely contribute to increased blood pressure inhypertensive patients. The reduction of renal blood flow and glomerularfiltration rate as a result of renal sympathetic efferent stimulation islikely a cornerstone of the loss of renal function in cardio-renalsyndrome (i.e., renal dysfunction as a progressive complication ofchronic heart failure). Pharmacologic strategies to thwart theconsequences of renal efferent sympathetic stimulation include centrallyacting sympatholytic drugs, beta blockers (intended to reduce reninrelease), angiotensin converting enzyme inhibitors and receptor blockers(intended to block the action of angiotensin II and aldosteroneactivation consequent to renin release), and diuretics (intended tocounter the renal sympathetic mediated sodium and water retention).These pharmacologic strategies, however, have significant limitationsincluding limited efficacy, compliance issues, side effects, and others.Recently, intravascular devices that reduce sympathetic nerve activityby applying an energy field to a target site in the renal blood vessel(e.g., via RF ablation) have been shown to reduce blood pressure inpatients with treatment-resistant hypertension.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present disclosure. Furthermore,components can be shown as transparent in certain views for clarity ofillustration only and not to indicate that the illustrated component isnecessarily transparent.

FIG. 1 is a partially schematic diagram of a neuromodulation systemconfigured in accordance with an embodiment of the present technology.

FIG. 2 illustrates modulating renal nerves with a multi-electrodecatheter configured in accordance with an embodiment of the presenttechnology.

FIG. 3A is a side view of a distal portion of a catheter having atherapeutic assembly or treatment section in a delivery state (e.g.,low-profile or collapsed configuration) outside a patient in accordancewith an embodiment of the present technology.

FIG. 3B is a perspective view of the distal portion of the catheter ofFIG. 3A in a deployed state (e.g., expanded configuration) outside thepatient.

FIG. 4 is an enlarged view of a portion of the treatment device of FIG.3A.

FIG. 5 is a partially schematic side view of a loading tool configuredin accordance with an embodiment of the present technology.

DETAILED DESCRIPTION

The present technology is directed to apparatuses, systems, and methodsfor achieving electrically- and/or thermally-induced renalneuromodulation (i.e., rendering neural fibers that innervate the kidneyinert or inactive or otherwise completely or partially reduced infunction) by percutaneous transluminal intravascular access. Inparticular, embodiments of the present technology relate to cathetersand catheter assemblies having multi-electrode arrays and being movablebetween a delivery or low-profile state (e.g., a generally straightshape) and a deployed state (e.g., a radially expanded, generallyhelical shape). The electrodes or energy delivery elements comprisingthe multi-electrode array are configured to deliver energy (e.g.,electrical energy, RF energy, pulsed electrical energy, thermal energy)to a renal artery after being advanced thereto via a catheter along apercutaneous transluminal path (e.g., a femoral artery puncture, aniliac artery and the aorta, a radial artery, or another suitableintravascular path). The catheter or catheter assembly carrying themulti-electrode array is sized and shaped so that the electrodes orenergy delivery elements contact an interior wall of the renal arterywhen the catheter is in the deployed (e.g., helical) state within therenal artery. In addition, the helical shape of the deployed portion ofthe catheter carrying the array allows blood to flow through the helix,which is expected to help prevent occlusion of the renal artery duringactivation of the energy delivery element. Further, blood flow in andaround the array may cool the associated energy delivery elements and/orthe surrounding tissue. In some embodiments, cooling the energy deliveryelements allows for the delivery of higher power levels at lowertemperatures than may be reached without cooling. This feature isexpected to help create deeper and/or larger lesions during therapy,reduce intimal surface temperature, and/or allow longer activation timeswith reduced risk of overheating during treatment.

Specific details of several embodiments of the technology are describedbelow with reference to FIGS. 1-5. Although many of the embodiments aredescribed below with respect to devices, systems, and methods forintravascular modulation of renal nerves using multi-electrode arrays,other applications and other embodiments in addition to those describedherein are within the scope of the technology. Additionally, severalother embodiments of the technology can have different configurations,components, or procedures than those described herein. A person ofordinary skill in the art, therefore, will accordingly understand thatthe technology can have other embodiments with additional elements, orthe technology can have other embodiments without several of thefeatures shown and described below with reference to FIGS. 1-5.

As used herein, the terms “distal” and “proximal” define a position ordirection with respect to the treating clinician or clinician's controldevice (e.g., a handle assembly). “Distal” or “distally” are a positiondistant from or in a direction away from the clinician or clinician'scontrol device. “Proximal” and “proximally” are a position near or in adirection toward the clinician or clinician's control device.

I. RENAL NEUROMODULATION

Renal neuromodulation is the partial or complete incapacitation or othereffective disruption of nerves innervating the kidneys. In particular,renal neuromodulation comprises inhibiting, reducing, and/or blockingneural communication along neural fibers (i.e., efferent and/or afferentnerve fibers) innervating the kidneys. Such incapacitation can belong-term (e.g., permanent or for periods of months, years, or decades)or short-term (e.g., for periods of minutes, hours, days, or weeks).Renal neuromodulation is expected to efficaciously treat severalclinical conditions characterized by increased overall sympatheticactivity, and in particular conditions associated with centralsympathetic over stimulation such as hypertension, heart failure, acutemyocardial infarction, metabolic syndrome, insulin resistance, diabetes,left ventricular hypertrophy, chronic and end stage renal disease,inappropriate fluid retention in heart failure, cardio-renal syndrome,osteoporosis, and sudden death. The reduction of afferent neural signalscontributes to the systemic reduction of sympathetic tone/drive, andrenal neuromodulation is expected to be useful in treating severalconditions associated with systemic sympathetic over activity orhyperactivity. Renal neuromodulation can potentially benefit a varietyof organs and bodily structures innervated by sympathetic nerves.

Various techniques can be used to partially or completely incapacitateneural pathways, such as those innervating the kidney. The purposefulapplication of energy (e.g., electrical energy, thermal energy) totissue by energy delivery element(s) can induce one or more desiredthermal heating effects on localized regions of the renal artery andadjacent regions of the renal plexus, which lay intimately within oradjacent to the adventitia of the renal artery. The purposefulapplication of the thermal heating effects can achieve neuromodulationalong all or a portion of the renal plexus.

The thermal heating effects can include both thermal ablation andnon-ablative thermal alteration or damage (e.g., via sustained heatingand/or resistive heating). Desired thermal heating effects may includeraising the temperature of target neural fibers above a desiredthreshold to achieve non-ablative thermal alteration, or above a highertemperature to achieve ablative thermal alteration. For example, thetarget temperature can be above body temperature (e.g., approximately37° C.) but less than about 45° C. for non-ablative thermal alteration,or the target temperature can be about 45° C. or higher for the ablativethermal alteration.

More specifically, exposure to thermal energy (heat) in excess of a bodytemperature of about 37° C., but below a temperature of about 45° C.,may induce thermal alteration via moderate heating of the target neuralfibers or of vascular structures that perfuse the target fibers. Incases where vascular structures are affected, the target neural fibersare denied perfusion resulting in necrosis of the neural tissue. Forexample, this may induce non-ablative thermal alteration in the fibersor structures. Exposure to heat above a temperature of about 45° C., orabove about 60° C., may induce thermal alteration via substantialheating of the fibers or structures. For example, such highertemperatures may thermally ablate the target neural fibers or thevascular structures. In some patients, it may be desirable to achievetemperatures that thermally ablate the target neural fibers or thevascular structures, but that are less than about 90° C., or less thanabout 85° C., or less than about 80° C., and/or less than about 75° C.Regardless of the type of heat exposure utilized to induce the thermalneuromodulation, a reduction in renal sympathetic nerve activity (RSNA)is expected.

II. SELECTED EMBODIMENTS OF NEUROMODULATION SYSTEMS

FIG. 1 illustrates a renal neuromodulation system 10 (“system 10”)configured in accordance with an embodiment of the present technology.The system 10 includes an intravascular catheter 12 operably coupled toan energy source or energy generator 26 (e.g., a RF energy generator).The catheter 12 can include an elongated shaft 16 having a proximalportion 18, a handle 34 at a proximal region of the proximal portion 18,and a distal portion 20. The catheter 12 can further include atherapeutic assembly or treatment section 21 (shown schematically) atthe distal portion 20 (e.g., attached to the distal portion 20, defininga section of the distal portion 20, etc.). As explained in furtherdetail below, the therapeutic assembly 21 can include a supportstructure 22 and an array of two or more energy delivery elements 24(e.g., electrodes) configured to be delivered to a renal blood vessel(e.g., a renal artery) in a low-profile configuration. Upon delivery tothe target treatment site within the renal blood vessel, the therapeuticassembly 21 is further configured to be deployed into an expanded state(e.g., a generally spiral/helical configuration) for delivering energyat the treatment site and providing therapeutically-effectiveelectrically- and/or thermally-induced renal neuromodulation.Alternatively, the deployed state may be non-helical provided that thedeployed state delivers the energy to the treatment site. Thetherapeutic assembly 21 may be transformed between the delivery anddeployed states using a variety of suitable mechanisms or techniques(e.g., self-expansion, remote actuation via an actuator, etc.).

The proximal end of the therapeutic assembly 21 is carried by or affixedto the distal portion 20 of the elongated shaft 16. A distal end of thetherapeutic assembly 21 may terminate the catheter 12 with, for example,an atraumatic tip 40. In some embodiments, the distal end of thetherapeutic assembly 21 may also be configured to engage another elementof the system 10 or catheter 12. For example, the distal end of thetherapeutic assembly 21 may define a passageway for receiving a guidewire (not shown) for delivery of the treatment device usingover-the-wire (“OTW”) or rapid exchange (“RX”) techniques. Furtherdetails regarding such arrangements are described below.

The catheter 12 can be electrically coupled to the energy source 26 viaa cable 28, and the energy source 26 (e.g., a RF energy generator) canbe configured to produce a selected modality and magnitude of energy fordelivery to the treatment site via the energy delivery elements 24. Asdescribed in greater detail below, supply wires (not shown) can extendalong the elongated shaft 16 or through a lumen in the shaft 16 to theindividual energy delivery elements 24 and transmit the treatment energyto the energy delivery elements 24. In some embodiments, each energydelivery element 24 includes its own supply wire. In other embodiments,however, two or more energy delivery elements 24 may be electricallycoupled to the same supply wire. A control mechanism 32, such as footpedal or handheld remote control device, may be connected to the energysource 26 to allow the clinician to initiate, terminate and, optionally,adjust various operational characteristics of the energy source 26,including, but not limited to, power delivery. The remote control device(not shown) can be positioned in a sterile field and operably coupled tothe energy delivery elements 24, and can be configured to allow theclinician to selectively activate and deactivate the energy deliveryelements 24. In other embodiments, the remote control device may bebuilt into the handle assembly 34.

The energy source or energy generator 26 can be configured to deliverthe treatment energy via an automated control algorithm 30 and/or underthe control of a clinician. For example, the energy source 26 caninclude computing devices (e.g., personal computers, server computers,tablets, etc.) having processing circuitry (e.g., a microprocessor) thatis configured to execute stored instructions relating to the controlalgorithm 30. In addition, the processing circuitry may be configured toexecute one or more evaluation/feedback algorithms 31, which can becommunicated to the clinician. For example, the energy source 26 caninclude a monitor or display 33 and/or associated features that areconfigured to provide visual, audio, or other indications of powerlevels, sensor data, and/or other feedback. The energy source 26 canalso be configured to communicate the feedback and other information toanother device, such as a monitor in a catheterization laboratory.

The energy delivery elements 24 may be configured to deliver powerindependently (i.e., may be used in a monopolar fashion), eithersimultaneously, selectively, or sequentially, and/or may deliver powerbetween any desired combination of the elements (i.e., may be used in abipolar fashion). In monopolar embodiments, a neutral or dispersiveelectrode 38 may be electrically connected to the energy generator 26and attached to the exterior of the patient (e.g., as shown in FIG. 2).Furthermore, the clinician optionally may choose which energy deliveryelement(s) 24 are used for power delivery in order to form highlycustomized lesion(s) within the renal artery having a variety of shapesor patterns. In still other embodiments, the system 10 can be configuredto deliver other suitable forms of treatment energy, such as acombination of monopolar and bipolar electric fields.

In several embodiments, the energy source 26 may include aradio-frequency identification (RFID) evaluation module (not shown)mounted at or near one or more ports on the energy source 26 andconfigured to wirelessly read and write to one or more RFID tags (notshown) on the catheter 12. In one particular embodiment, for example,the catheter 12 may include an RFID tag housed within or otherwiseattached to the connector portion of the cable 28 that is coupled to theenergy source 26. The RFID tag can include, for example, an antenna andan RFID chip for processing signals, sending/receiving RF signals, andstoring data in memory. Suitable RFID tags include, for example,MB89R118 RFID tags available from Fujitsu Limited of Tokyo, Japan. Thememory portion of the RFID tag can include a plurality of blocksallocated for different types of data. For example, a first memory blockcan include a validation identifier (e.g., a unique identifierassociated with the specific type of catheter and generated from theunique ID of the RFID tag using an encrypting algorithm), and a secondmemory block can be allocated as a catheter usage counter that can beread and then written to by the RFID module carried by the energy source26 after catheter use. In other embodiments, the RFID tag can includeadditional memory blocks allocated for additional catheter usagecounters (e.g., to allow the catheter 12 to be used a specific limitednumber of times) and/or other information associated with the catheter12 (e.g., lot number, customer number, catheter model, summary data,etc.).

The RFID evaluation module carried by the energy source 26 can includean antenna and a processing circuit that are together used tocommunicate with one or more portions of the energy source 26 andwirelessly read/write to one or more RFID tag within its proximity(e.g., when the cable 28 including an RFID tag is attached to the energysource 26). Suitable RFID evaluation modules include, for example, aTRF7960A Evaluation Module available from Texas Instruments Incorporatedof Dallas, Tex.

In operation, the RFID evaluation module is configured to readinformation from the RFID tag (carried by the cable 28 or anothersuitable portion of the catheter 12), and communicate the information tosoftware of the energy source 26 to validate the attached catheter 12(e.g., validate that the catheter 12 is compatible with the energysource 26), read the number of previous uses associated with theparticular catheter 12, and/or write to the RFID tag to indicatecatheter use. In various embodiments, the energy source 26 may beconfigured to disable energy delivery to the catheter 12 when predefinedconditions of the RFID tag are not met. For example, when each thecatheter 12 is connected to the energy source 26, the RFID evaluationmodule can read a unique anti-counterfeit number in an encrypted formatfrom the RFID tag, decrypt the number, and then authenticate the numberand the catheter data format for recognized catheters (e.g., cathetersthat are compatible with the particular energy source 26,non-counterfeit catheters, etc.). In various embodiments, the RFID tagcan include identifier(s) that correspond to a specific type ofcatheter, and the RFID evaluation module can transmit this informationto a main controller of the energy source 26, which can adjust thesettings (e.g., the control algorithm 30) of the energy source 26 to thedesired operating parameters/characteristics (e.g., power levels,display modes, etc.) associated with the specific catheter. Further, ifthe RFID evaluation module identifies the catheter 12 as counterfeit oris otherwise unable to identify the catheter 12, the energy source 26can automatically disable the use of the catheter 12 (e.g., precludeenergy delivery).

Once the catheter 12 has been identified, the RFID evaluation module canread the RFID tag memory address spaces to determine if the catheter 12was previously connected to a generator (i.e., previous used). Incertain embodiments, the RFID tag may limit the catheter 12 to a singleuse, but in other embodiments the RFID tag can be configured to providefor more than one use (e.g., 2 uses, 5 uses, 10 uses, etc.). If the RFIDevaluation module recognizes that the catheter 12 has been written(i.e., used) more than a predetermined use limit, the RFID module cancommunicate with the energy source 26 to disable energy delivery to thecatheter 12. In certain embodiments, the RFID evaluation module can beconfigured to interpret all the catheter connections to an energy sourcewithin a predefined time period (e.g., 5 hours, 10 hours, 24 hours, 30hours, etc.) as a single connection (i.e., a single use), and allow thecatheter 12 to be used multiple times within the predefined time period.After the catheter 12 has been detected, recognized, and judged as a“new connection” (e.g., not used more than the predefined limit), theRFID evaluation module can write to the RFID tag (e.g., the time anddate of the system use and/or other information) to indicate that thecatheter 12 has been used. In other embodiments, the RFID evaluationmodule and/or RFID tag may have different features and/or differentconfigurations.

The system 10 can also include one or more sensors (not shown) locatedproximate to or within the energy delivery elements 24. For example, thesystem 10 can include temperature sensors (e.g., thermocouple,thermistor, etc.), impedance sensors, pressure sensors, optical sensors,flow sensors, and/or other suitable sensors connected to one or moresupply wires (not shown) that transmit signals from the sensors and/orconvey energy to the energy delivery elements 24. FIG. 2 (withadditional reference to FIG. 1) illustrates modulating renal nerves withan embodiment of the system 10. The catheter 12 provides access to therenal plexus RP through an intravascular path P, such as a percutaneousaccess site in the femoral (illustrated), brachial, radial, or axillaryartery to a targeted treatment site within a respective renal artery RA.As illustrated, a section of the proximal portion 18 of the shaft 16 isexposed externally of the patient. By manipulating the proximal portion18 of the shaft 16 from outside the intravascular path P, the clinicianmay advance the shaft 16 through the sometimes tortuous intravascularpath P and remotely manipulate the distal portion 20 of the shaft 16. Inthe embodiment illustrated in FIG. 2, the therapeutic assembly 21 isdelivered intravascularly to the treatment site using a guide wire 66 inan OTW technique. As noted previously, the distal end of the therapeuticassembly 21 may define a lumen or passageway for receiving the guidewire 66 for delivery of the catheter 12 using either OTW or RXtechniques. At the treatment site, the guide wire 66 can be at leastpartially axially withdrawn or removed, and the therapeutic assembly 21can transform or otherwise be moved to a deployed arrangement fordelivering energy at the treatment site. Further details regarding sucharrangements are described below with reference to FIGS. 3A and 3B. Theguide wire 66 may comprise any suitable medical guide wire sized toslidably fit within the lumen. In one particular embodiment, forexample, the guide wire 66 may have a diameter of 0.356 mm (0.014 inch).In other embodiments, the therapeutic assembly 21 may be delivered tothe treatment site within a guide sheath (not shown) with or withoutusing the guide wire 66. When the therapeutic assembly 21 is at thetarget site, the guide sheath may be at least partially withdrawn orretracted and the therapeutic assembly 21 can be transformed into thedeployed arrangement. Additional details regarding this type ofconfiguration are described below. In still other embodiments, the shaft16 may be steerable itself such that the therapeutic assembly 21 may bedelivered to the treatment site without the aid of the guide wire 66and/or guide sheath.

Image guidance, e.g., computed tomography (CT), fluoroscopy,intravascular ultrasound (IVUS), optical coherence tomography (OCT),intracardiac echocardiography (ICE), or another suitable guidancemodality, or combinations thereof, may be used to aid the clinician'spositioning and manipulation of the therapeutic assembly 21. Forexample, a fluoroscopy system (e.g., including a flat-panel detector,x-ray, or c-arm) can be rotated to accurately visualize and identify thetarget treatment site. In other embodiments, the treatment site can bedetermined using IVUS, OCT, and/or other suitable image mappingmodalities that can correlate the target treatment site with anidentifiable anatomical structure (e.g., a spinal feature) and/or aradiopaque ruler (e.g., positioned under or on the patient) beforedelivering the catheter 12. Further, in some embodiments, image guidancecomponents (e.g., IVUS, OCT) may be integrated with the catheter 12and/or run in parallel with the catheter 12 to provide image guidanceduring positioning of the therapeutic assembly 21. For example, imageguidance components (e.g., IVUS or OCT) can be coupled to at least oneof the therapeutic assembly 21 (e.g., proximal to the therapeutic arms25) to provide three-dimensional images of the vasculature proximate thetarget site to facilitate positioning or deploying the multi-electrodeassembly within the target renal blood vessel.

The purposeful application of energy from the energy delivery elements24 may then be applied to target tissue to induce one or more desiredneuromodulating effects on localized regions of the renal artery andadjacent regions of the renal plexus RP, which lay intimately within,adjacent to, or in close proximity to the adventitia of the renal arteryRA. The purposeful application of the energy may achieve neuromodulationalong all or at least a portion of the renal plexus RP. Theneuromodulating effects are generally a function of, at least in part,power, time, contact between the energy delivery elements 24 (FIG. 1)and the vessel wall, and blood flow through the vessel. Theneuromodulating effects may include denervation, thermal ablation,and/or non-ablative thermal alteration or damage (e.g., via sustainedheating and/or resistive heating). Desired thermal heating effects mayinclude raising the temperature of target neural fibers above a desiredthreshold to achieve non-ablative thermal alteration, or above a highertemperature to achieve ablative thermal alteration. For example, thetarget temperature may be above body temperature (e.g., approximately37° C.) but less than about 45° C. for non-ablative thermal alteration,or the target temperature may be about 45° C. or higher for the ablativethermal alteration. Desired non-thermal neuromodulation effects mayinclude altering the electrical signals transmitted in a nerve.

FIG. 3A is a side view of the distal portion 20 of the catheter 12 andthe therapeutic assembly or treatment section 21 in a delivery state(e.g., low-profile or collapsed configuration) outside a patient, andFIG. 3B is a perspective view of the therapeutic assembly 21 in adeployed state (e.g., expanded configuration) outside the patient. Asdescribed previously, the catheter 12 may be configured for OTW deliveryfrom an access site in which the guide wire 66 (FIG. 2) is initiallyinserted to a treatment site (e.g., within a renal artery), and thecatheter 12 is installed over the guide wire. As described in greaterdetail below, a guide wire may be either inserted into or at leastpartially withdrawn from the distal portion 20 to transform thetherapeutic assembly 21 between the delivery state (FIG. 3A) and thedeployed state (FIG. 3B). For example, as shown in FIG. 3A, a guide wire(not shown) extending through at least a portion of the length of thecatheter 12 may be configured to straighten a pre-shaped spiral/helicalcontrol member 50 (shown schematically in broken lines) of the catheter12 during delivery, and the guide wire may be at least partiallywithdrawn or slidably moved relative to the distal portion 20 to allowthe therapeutic assembly 21 to transform to the deployed state (FIG.3B).

As best seen in FIG. 3A, the therapeutic assembly 21 includes multiple(e.g., four, five, etc.) energy delivery elements 24 carried by thesupport structure 22. In this embodiment, the support structure 22comprises a flexible tube 42 and the pre-shaped control member 50 withinthe tube 42. The flexible tube 42 may be composed of a polymer materialsuch as polyamide, polyimide, polyether block amide copolymer sold underthe trademark PEBAX, polyethylene terephthalate (PET), polypropylene,aliphatic, polycarbonate-based thermoplastic polyurethane sold under thetrademark CARBOTHANE, or a polyether ether ketone (PEEK) polymer thatprovides the desired flexibility. In other embodiments, however, thetube 42 may be composed of other suitable materials.

As mentioned above, the pre-shaped control member 50 may be used toprovide a spiral/helical shape to the relatively flexible distal portion20 of the catheter 12. As best seen in FIG. 3B, for example, the controlmember 50 is a tubular structure comprising a nitinol multifilarstranded wire with a lumen therethrough and sold under the trademarkHELICAL HOLLOW STRAND (HHS), and commercially available from Fort WayneMetals of Fort Wayne, Ind. The tubular control member 50 may be formedfrom a variety of different types of materials, may be arranged in asingle or dual-layer configuration, and may be manufactured with aselected tension, compression, torque and pitch direction. The HHSmaterial, for example, may be cut using a laser, electrical dischargemachining (EDM), electrochemical grinding (ECG), or other suitable meansto achieve a desired finished component length and geometry. Forexample, as best seen in FIG. 3B, the control member 50 in the presentembodiment has a pre-set spiral/helical configuration that defines thedeployed state of the therapeutic assembly 21 such that the energydelivery elements 24 of the therapeutic assembly 21 are offset from eachother (e.g., both angularly and longitudinally offset relative to alongitudinal axis of the renal artery) and may be positioned in stableapposition with a wall of the renal artery (FIG. 2) for treatment. Forpurposes of clarification, the pre-set helical shape of the therapeuticassembly 21 in its deployed state may be defined by dimensions (e.g.,helix diameter and pitch) that are distinct from the dimensions (e.g.,helix diameter and pitch) of the HHS itself. In other words, themultifilar hollow tube forming control member 50 is itself pre-set intoa helical shape.

Forming the control member 50 of nitinol multifilar stranded wire(s) orother similar materials is expected to eliminate the need for anyadditional reinforcement wire(s) or structures within the supportstructure 22 to provide a desired level of support and rigidity to thetherapeutic assembly 21. This feature is expected to reduce the numberof manufacturing processes required to form the catheter 12 and reducethe number of materials required for the device. Another feature of thetherapeutic assembly 21 is that the control member 50 and inner wall ofthe tube 42 are in intimate contact and there is little or no spacebetween the control member 50 and the tube 42 (as best seen in FIG. 4).In one embodiment, for example, tube 42 can be expanded prior toassembly such that applying hot air to the tube 42 during themanufacturing process can shrink the tube onto the control member 50, aswill be understood by those familiar with the ordinary use of shrinktubing materials. This feature is expected to inhibit or eliminatewrinkles or kinks that might occur in the tube 42 as the therapeuticassembly 21 transforms from the relatively straight delivery state tothe deployed, generally helical state.

In other embodiments, the control member 50 and/or other components ofthe support structure 22 may be composed of different materials and/orhave a different arrangement. For example, the control member 50 may beformed from other suitable shape memory materials (e.g., nickel-titanium(nitinol), wire or tubing besides HHS, shape memory polymers,electro-active polymers) that are pre-formed or pre-shaped into thedesired deployed state. Alternatively, the control member 50 may beformed from multiple materials such as a composite of one or morepolymers and metals.

The array of energy delivery elements 24 can include series of separateband electrodes spaced along the support structure 22 and bonded to thetube 42 using an adhesive. Band or tubular electrodes may be used insome embodiments, for example, because they typically have lower powerrequirements for ablation as compared to disc or flat electrodes. Inother embodiments, however, disc or flat electrodes are also suitable.In still another embodiment, electrodes having a spiral or coil shapemay be utilized. In some embodiments, the energy delivery elements 24may be equally spaced apart along the length of the support structure22. The energy delivery elements 24 may be formed from any suitablemetallic material (e.g., gold, platinum, an alloy of platinum andiridium, etc.). In other embodiments, however, the number, arrangement,and/or composition of the energy delivery elements 24 may vary.

FIG. 4 is an enlarged view of a portion of the catheter 12 of FIG. 3A.Referring to FIGS. 1 and 4 together, each energy delivery element orelectrode 24 is electrically connected to the energy source 26 (FIG. 1)by a conductor or bifilar wire 44 extending through a lumen of the tube42. Each energy delivery element 24 may be welded or otherwiseelectrically coupled to its energy supply wire 44, and each wire 44 canextend through the tube 42 and elongated shaft 16 (FIG. 1) for theentire length of the shaft such that a proximal end thereof is coupledto the energy source 26 (FIG. 1). As noted above, the tube 42 isconfigured to fit tightly against the control member 50 and wires 44 tominimize the space between an inner portion of the tube 42 and thecomponents positioned therein to help prevent the formation of wrinklesin the therapeutic assembly 21 during deployment. In some embodiments,the catheter 12 may also include an insulating layer (e.g., a layer ofPET or another suitable material) over the control member 50 to furtherelectrically isolate the material (e.g., HHS) of the control member 50from the wires 44.

As best seen in FIG. 4, each energy delivery element 24 may includetapered end portions 24a (e.g., fillets) configured to provide an obtuseangle between an outer surface of the tube 42 and an outer surface ofthe corresponding energy delivery element 24. The smooth transition inangle provided by the tapered end portions 24a is expected to helpprevent a guide sheath or loading tool from getting stuck or catchingthe edges of the energy delivery elements 24 as the guide sheath orloading tool is moved over the length of the therapeutic assembly 21(FIGS. 3A and 3B) during advancement and retrieval. In otherembodiments, the extent of the tapered portions 24a on the energydelivery elements 24 may vary. In some embodiments, the tapered endportions 24a comprise fillets formed from adhesive material at eitherend of the corresponding energy delivery elements 24. In otherembodiments, however, the tapered end portions 24a may be formed fromthe same material as the tube 42 (e.g., integrally formed with the tube42 or formed separately and attached to either end of correspondingenergy delivery elements 24). Further, the tapered portions 24a are anoptional feature that may not be included in some embodiments.

Referring back to FIGS. 3A and 3B, the therapeutic assembly 21 includesthe atraumatic, flexible curved tip 40 at a distal end of the assembly21. The curved tip 40 is configured to provide a distal opening 41 forthe guide wire 66 (FIG. 2) that directs the guide wire away from thewall of the renal artery when the therapeutic assembly 21 is in thepre-set deployed configuration. This feature is expected to facilitatealignment of the helical therapeutic assembly 21 in the renal bloodvessel as it expands, while also reducing the risk of injuring the bloodvessel wall when the guide wire distal tip is advanced from the opening41. The curvature of the tip 40 can be varied depending upon theparticular sizing/configuration of the therapeutic assembly 21. As bestseen in FIG. 3B, for example, in the illustrated embodiment the tip 40is curved such that it is off the pre-set spiral/helical axis defined bythe control member 50. In other embodiments, however, the tip 40 mayhave a different curvature. In some embodiments, the tip 40 may alsocomprise one or more radiopaque markers 52 and/or one or more sensors(not shown). The tip 40 can be affixed to the distal end of the supportstructure 22 via adhesive, crimping, over-molding, or other suitabletechniques.

The flexible curved tip 40 can be made from a polymer material (e.g.,polyether block amide copolymer sold under the trademark PEBAX), athermoplastic polyether urethane material (sold under the trademarksELASTHANE or PELLETHANE), or other suitable materials having the desiredproperties, including a selected durometer. As noted above, the tip 40is configured to provide an opening for the guide wire 66, and it isdesirable that the tip itself maintain a desired shape/configurationduring operation. Accordingly, in some embodiments, one or moreadditional materials may be added to the tip material to help improvetip shape retention. In one particular embodiment, for example, about 5to 30 weight percent of siloxane can be blended with the tip material(e.g., the thermoplastic polyether urethane material), and electron beamor gamma irradiation may be used to induce cross-linking of thematerials. In other embodiments, the tip 40 may be formed from differentmaterial(s) and/or have a different arrangement.

In operation (and with reference to FIGS. 2, 3A, and 3B), afterpositioning the therapeutic assembly 21 at the desired location withinthe renal artery RA of the patient, the therapeutic assembly 21 may betransformed from its delivery state to its deployed state or deployedarrangement. The transformation may be initiated using an arrangement ofdevice components as described herein with respect to the particularembodiments and their various modes of deployment. In one embodiment,for example, the therapeutic assembly 21 may be deployed by retractingthe guide wire 66 until a distal tip of the guide wire 66 is generallyaligned with the tip 40 of the catheter 12. In some embodiments, theguide wire 66 may have a varying stiffness or flexibility along itslength so as to provide increased flexibility distally. When the varyingflexible guide wire 66 is partially retracted as described above, thepre-set helical shape of the control member 50 provides a shape-recoveryforce sufficient to overcome the straightening force provided by thedistalmost portion of the guide wire 66 such that the therapeuticassembly 21 can deploy into its helical configuration. Further, becausethe flexible distal portion of the guide wire 66 remains within thetherapeutic assembly 21 in the deployed state, the guide wire 66 canimpart additional structural integrity to the helically-shaped portionduring treatment. This feature is expected to help mitigate or reduceproblems associated with keeping the therapeutic assembly 21 in placeduring treatment (e.g., help with vasoconstriction).

In another embodiment, the guide wire 66 may have a stiffness profilethat permits the distal portion of the guide wire 66 to remain extendedfrom the opening 41 while still permitting the therapeutic assembly 21to transform to its deployed configuration. In still other embodiments,the guide wire 66 may be withdrawn completely from the therapeuticassembly 21 (e.g., a distalmost end portion of the guide wire 66 isproximal of the therapeutic assembly 21) to permit the transformation,while a distalmost portion of the guide wire 66 remains within the shaft16. In yet another embodiment, the guide wire 66 may be withdrawncompletely from the shaft 16. In any of the foregoing examples, theclinician can withdraw the guide wire 66 sufficiently to observetransformation of the therapeutic assembly 21 to the deployedconfiguration and/or until an X-ray image shows that the distal tip ofthe guide wire 66 is at a desired location relative to the therapeuticassembly 21 (e.g., generally aligned with the tip 40, completelywithdrawn from the therapeutic assembly 21, etc.). In some embodiments,the extent of withdrawal for the guide wire 66 can be based, at least inpart, on the clinician's judgment with respect to the selected guidewire and the extent of withdrawal necessary to achieve deployment.

After treatment, the therapeutic assembly 21 may be transformed back tothe low-profile delivery configuration by axially advancing the guidewire 66 relative to the therapeutic assembly 21. In one embodiment, forexample, the guide wire 66 may be advanced until the distal tip of theguide wire 66 is generally aligned with the tip 40, and the catheter 12can then be pulled back over the stationary guide wire 66. In otherembodiments, however, the distalmost portion of the guide wire 66 may beadvanced to different location relative to the therapeutic assembly 21to achieve transformation of the therapeutic assembly 21 back tolow-profile arrangement.

The embodiments of the catheter systems described above include aprocedural guide wire to guide the catheter to the treatment site andalso to restrain the therapeutic assembly or treatment section in alow-profile delivery state. In further embodiments, catheter systemsconfigured in accordance with the present technology may further includean external loading tool that can be disposed and retracted over thetherapeutic assembly to further assist with transforming the therapeuticassembly between the delivery and deployed configurations.

FIG. 5, for example, is a partially schematic side view of a loadingtool 190 in accordance with an embodiment of the present technology. Theloading tool 190 is a tubular structure configured to slidably movealong an outer surface of the shaft 16 and the therapeutic assembly 21(for purposes of illustration, the therapeutic assembly 21 andassociated features are shown in broken lines). The loading tool 190 hasa size and stiffness suitable for maintaining the therapeutic assembly21 in the low-profile configuration for backloading of the guide wire 66(FIG. 2), i.e., insertion of the proximal end of guide wire 66 into thedistal opening 41. In the illustrated embodiment, the loading tool 190can include a tapered portion 192 to help facilitate advancement of thesheath over the therapeutic assembly 21 and the associated energydelivery elements 24. In some embodiments, a distal portion 194 of theloading tool 190 may also include smooth, rounded inner and outer edges195 to help ease the inner wall of the loading tool over the energydelivery elements 24 during advancement of the loading tool relative tothe therapeutic assembly 21. The loading tool 190 may be composed ofhigh-density polyethylene (HDPE) or other suitable materials having adesired strength and lubricity. In still other embodiments, the loadingtool 190 may be composed of two or more different materials. In oneembodiment, for example, the larger diameter section of the loading tool190 distal of the tapered portion 192 may be composed of HDPE, while thesmaller diameter section of the loading tool 190 proximal of the taperedportion 192 may be composed of linear low-density polyethylene (LLDPE).In still further embodiments, the loading tool 190 may be composed ofdifferent materials and/or have a different arrangement.

In some embodiments, the loading tool 190 may be used in conjunctionwith the catheter 12 while the catheter 12 is external to the patientbefore treatment, and then removed from the catheter 12 before thecatheter 12 is inserted into the patient. More specifically, asdiscussed above, the loading tool 190 can be used to maintain thetherapeutic assembly 21 in the low-profile configuration while the guidewire is backloaded (moving from a distal end toward a proximal end ofthe catheter 12). The loading tool 190 can then be removed from thecatheter 12, and the therapeutic assembly 21 can be restrained in thedelivery configuration with the support of the guide wire. In anotherembodiment, the loading tool 190 may remain installed on the catheter 12after backloading of the guide wire, but may be slid down the length ofthe catheter 12 to a proximal portion 18 of the catheter 12 near thehandle 34 (FIG. 1). In this way, the loading tool 190 remains with thecatheter 12, but is out of the way during treatment.

In still other embodiments, however, the loading tool 190 may remain ator near the distal portion 20 (FIG. 1) of the catheter 12 duringtreatment. For example, in one embodiment, a clinician may keep theloading tool 190 at or near the distal portion 20 of the catheter 12 andthen insert the loading tool 190 into a hemostasis valve (not shown)connected to a guide catheter (not shown). Depending upon a profile ofthe loading tool 190 and an inner diameter of the hemostasis valve, theclinician may be able to insert approximately 2 to 4 cm of the loadingtool 190 into the hemostasis valve. One advantage of this approach isthat the therapeutic assembly 21 (FIGS. 3A and 3B) is further protectedas the catheter 12 is advanced through the hemostasis valve, and theclinician is expected to feel little or no friction between the catheter12 and the hemostasis valve. In other embodiments, however, the loadingtool 190 may have a different arrangement relative to the hemostasisvalve and/or the other components of the system 10 (FIG. 1) duringoperation.

III. FURTHER EXAMPLES

The following examples are illustrative of several embodiments of thepresent technology:

1. A catheter apparatus, comprising:

-   -   an elongated tubular shaft having a proximal portion and a        distal portion; and    -   a therapeutic assembly disposed at the distal portion of the        elongated shaft and adapted to be located at a target location        within a renal artery of a human patient, the therapeutic        assembly including a support structure comprising        -   a control member comprising a pre-formed helical shape,            wherein the control member is a tubular structure having a            lumen therethrough and is composed of a nitinol multifilar            stranded wire; and        -   a plurality of energy delivery elements carried by the            support structure,    -   wherein the elongated tubular shaft and the therapeutic assembly        together define therethrough a guide wire lumen configured to        slidably receive a medical guide wire, and    -   wherein axial movement of the guide wire relative to the        therapeutic assembly transforms the support structure        between (a) a low-profile delivery configuration and (b) a        deployed configuration tending to assume the pre-formed helical        shape of the control member.

2. The catheter apparatus of example 1 wherein the therapeutic assemblyis configured to transform between the low-profile deliveryconfiguration and the deployed configuration while at least a distalportion of the guide wire remains in the guide wire lumen of thetherapeutic assembly.

3. The catheter apparatus of example 2 wherein the support structurecomprises a shape-recovery force sufficient to overcome a straighteningforce provided by a distal region of the guide wire to transform thetherapeutic assembly to the deployed configuration when a distalmost tipof the guide wire is generally aligned with a distal tip of thetherapeutic assembly.

4. The catheter apparatus of example 1 wherein:

-   -   the support structure comprises a shape-recovery force        insufficient to overcome a straightening force provided by a        distal region of the guide wire when the guide wire is within        the guide wire lumen of the therapeutic assembly; and    -   the therapeutic assembly is configured to transform to the        deployed configuration when a distalmost portion of the guide        wire is withdrawn though the guide wire lumen to a point        proximal of the therapeutic assembly.

5. The catheter apparatus of any one of examples 1 to 4 wherein a distalportion of the therapeutic assembly further comprises a flexible curvedtip configured to provide an opening for the guide wire and, in thedeployed configuration, to direct the guide wire away from a wall of therenal artery.

6. The catheter apparatus of example 5 wherein the flexible curved tipis composed of polyether block amide copolymer.

7. The catheter apparatus of example 5 wherein the flexible curved tipis composed of a thermoplastic polyether urethane material.

8. The catheter apparatus of example 7 wherein the flexible curved tipis composed of about 5 to 30 weight percent of siloxane blended with thethermoplastic polyether urethane material.

9. The catheter apparatus of any one of examples 1 to 8 wherein, in thedeployed configuration, the energy delivery elements carried by thesupport structure are spaced apart from each other along a longitudinalaxis of the renal artery and are configured to maintain apposition witha wall of the renal artery.

10. The catheter apparatus of any one of examples 1 to 9 wherein theenergy delivery elements comprise a series of band electrodes.

11. The catheter apparatus of example 10 wherein at least one of theband electrodes comprises tapered end portions, and wherein the taperedend portions are configured to provide an obtuse angle between an outersurface of the support structure and an outer surface of the at leastone band electrode.

12. The catheter apparatus of any one of examples 1 to 11 wherein thetherapeutic assembly comprises four energy delivery elements.

13. The catheter apparatus of any one of examples 1 to 12, furthercomprising a retractable loading tool surrounding and restraining atleast a longitudinal portion of the therapeutic assembly in thelow-profile delivery configuration.

14. The catheter apparatus of example 13 wherein the loading toolcomprises a distal end portion having rounded edges.

15. A renal neuromodulation system for treatment of a human patient, thesystem comprising:

-   -   an elongate shaft having a proximal end and a distal end,        wherein the distal end of the shaft is configured for        intravascular delivery over a procedural guide wire to a renal        artery of the patient;    -   a pre-shaped tubular spiral structure disposed at or proximate        to the distal end of the elongate shaft, wherein the spiral        structure is configured to transform between an unexpanded        configuration and an expanded configuration that tends to assume        the shape of the pre-shaped spiral structure, and wherein the        spiral structure is composed, at least in part, of multifilar        stranded nitinol wire; and    -   a plurality of electrodes associated with the spiral structure,    -   wherein the elongate shaft and the spiral structure together        define a guide wire lumen therethrough, and wherein        -   the guide wire lumen is configured to slidably receive the            procedural guide wire to locate the spiral structure at a            target treatment site within a renal blood vessel of the            patient and to restrain the spiral structure in the            unexpanded configuration, and wherein        -   proximal movement of the procedural guide wire through the            guide wire lumen relative to the spiral structure such that            a distal end portion of the guide wire is at least partially            within the guide wire lumen transforms the spiral structure            to the expanded configuration.

16. The system of example 15 wherein the procedural guide wire comprisesa distal portion having varying flexibility, and further wherein atleast a region of the distal portion of the guide wire is configured toremain within the portion of the guide wire lumen defined by the spiralstructure when the spiral structure is in the expanded configuration.

17. The system of example 15 or example 16, further comprising aflexible tube covering and in intimate contact with the spiralstructure.

18. The system of example 17 wherein the plurality of electrodes arebonded to the flexible tube using an adhesive material.

19. The system of any one of examples 15 to 18 wherein the plurality ofelectrodes are composed of gold.

20. The system of any one of examples 15 to 19 wherein the plurality ofelectrodes are individually connectable to an energy source external tothe patient, and wherein the energy source is capable of individuallycontrolling the energy delivered to each electrode during therapy.

21. A method of performing renal neuromodulation, the method comprising:

-   -   intravascularly delivering a renal neuromodulation catheter in a        low-profile delivery configuration over a guide wire to a target        treatment site within a renal blood vessel of a human patient        and at least proximate to a renal nerve of the patient, wherein        the renal neuromodulation catheter comprises        -   an elongated shaft; and        -   a multi-electrode array disposed at a distal portion of the            shaft and composed, at least in part, of a tubular structure            formed of multifilar nitinol wire;    -   withdrawing the guide wire in a proximal direction until the        catheter transforms from the low-profile delivery configuration        to a deployed configuration wherein the tubular structure has a        radially expanded, generally spiral shape configured to contact        the wall of the renal blood vessel and to allow blood to flow        through the vessel; and    -   selectively delivering energy to one or more electrodes of the        multi-electrode array to inhibit neural communication along the        renal nerve.

22. The method of example 21 wherein selectively delivering energy toone or more electrodes of the multi-electrode array comprises producinga plurality of lesions in a desired pattern along the renal bloodvessel.

23. The method of example 21 or example 22 wherein the individualelectrodes of the multi-electrode array are spaced sufficiently apartsuch that the lesions do not overlap.

24. The method of any one of examples 21 to 23, further comprisingattaching an external ground to an exterior of the patient, and whereinselectively delivering energy to one or more electrodes furthercomprises delivering an electric field in a monopolar fashion betweeneach of the electrodes and the external ground.

25. The method of any one of examples 21 to 23 wherein selectivelydelivering energy comprises selectively delivering an electric field ina bipolar fashion between the electrodes of the multi-electrode array.

26. The method of any one of examples 21 to 25 wherein withdrawing theguide wire in a proximal direction until the therapeutic assemblytransforms comprises only partially withdrawing the guide wire from thetherapeutic assembly such that at least a portion of the guide wireremains in the therapeutic assembly after the therapeutic assemblytransforms to the deployed configuration.

27. The method of any one of examples 21 to 25 wherein withdrawing theguide wire in a proximal direction until the therapeutic assemblytransforms comprises completely withdrawing the guide wire from thetherapeutic assembly such that a distalmost portion of the guide wire iswithdrawn to a point proximal of the therapeutic assembly.

28. The method of any one of examples 21 to 27 wherein the targettreatment site comprises a first target treatment site, and wherein themethod further comprises:

-   -   advancing the guide wire in a distal direction after selectively        delivering energy to the one or more electrodes of the        multi-electrode array to transform the multi-electrode array        from the deployed configuration back to the low-profile delivery        configuration;    -   repositioning the catheter at a second target treatment site        different than the first treatment site;    -   withdrawing the guide wire in a proximal direction to again        transform the therapeutic assembly from the delivery        configuration to the deployed configuration; and    -   selectively delivering energy to one or more electrodes of the        multi-electrode array positioned at the second target treatment        site.

IV. CONCLUSION

The above detailed descriptions of embodiments of the technology are notintended to be exhaustive or to limit the technology to the precise formdisclosed above. Although specific embodiments of, and examples for, thetechnology are described above for illustrative purposes, variousequivalent modifications are possible within the scope of thetechnology, as those skilled in the relevant art will recognize. Forexample, while steps are presented in a given order, alternativeembodiments may perform steps in a different order. The variousembodiments described herein may also be combined to provide furtherembodiments.

From the foregoing, it will be appreciated that specific embodiments ofthe technology have been described herein for purposes of illustration,but well-known structures and functions have not been shown or describedin detail to avoid unnecessarily obscuring the description of theembodiments of the technology. Where the context permits, singular orplural terms may also include the plural or singular term, respectively.

Moreover, unless the word “or” is expressly limited to mean only asingle item exclusive from the other items in reference to a list of twoor more items, then the use of “or” in such a list is to be interpretedas including (a) any single item in the list, (b) all of the items inthe list, or (c) any combination of the items in the list. Additionally,the term “comprising” is used throughout to mean including at least therecited feature(s) such that any greater number of the same featureand/or additional types of other features are not precluded. It willalso be appreciated that specific embodiments have been described hereinfor purposes of illustration, but that various modifications may be madewithout deviating from the technology. Further, while advantagesassociated with certain embodiments of the technology have beendescribed in the context of those embodiments, other embodiments mayalso exhibit such advantages, and not all embodiments need necessarilyexhibit such advantages to fall within the scope of the technology.Accordingly, the disclosure and associated technology can encompassother embodiments not expressly shown or described herein.

I/We claim:
 1. A catheter apparatus, comprising: an elongated tubular shaft having a proximal portion and a distal portion; and a therapeutic assembly disposed at the distal portion of the elongated shaft and adapted to be located at a target location within a renal artery of a human patient, the therapeutic assembly including a support structure comprising a control member comprising a pre-formed helical shape, wherein the control member is a tubular structure having a lumen therethrough and is composed of a nitinol multifilar stranded wire; and a plurality of energy delivery elements carried by the support structure, wherein the elongated tubular shaft and the therapeutic assembly together define therethrough a guide wire lumen configured to slidably receive a medical guide wire, and wherein axial movement of the guide wire relative to the therapeutic assembly transforms the support structure between (a) a low-profile delivery configuration and (b) a deployed configuration tending to assume the pre-formed helical shape of the control member.
 2. The catheter apparatus of claim 1 wherein the therapeutic assembly is configured to transform between the low-profile delivery configuration and the deployed configuration while at least a distal portion of the guide wire remains in the guide wire lumen of the therapeutic assembly.
 3. The catheter apparatus of claim 2 wherein the support structure comprises a shape-recovery force sufficient to overcome a straightening force provided by a distal region of the guide wire to transform the therapeutic assembly to the deployed configuration when a distalmost tip of the guide wire is generally aligned with a distal tip of the therapeutic assembly.
 4. The catheter apparatus of claim 1 wherein: the support structure comprises a shape-recovery force insufficient to overcome a straightening force provided by a distal region of the guide wire when the guide wire is within the guide wire lumen of the therapeutic assembly; and the therapeutic assembly is configured to transform to the deployed configuration when a distalmost portion of the guide wire is withdrawn though the guide wire lumen to a point proximal of the therapeutic assembly.
 5. The catheter apparatus of claim 1 wherein a distal portion of the therapeutic assembly further comprises a flexible curved tip configured to provide an opening for the guide wire and, in the deployed configuration, to direct the guide wire away from a wall of the renal artery.
 6. The catheter apparatus of claim 5 wherein the flexible curved tip is composed of polyether block amide copolymer.
 7. The catheter apparatus of claim 5 wherein the flexible curved tip is composed of a thermoplastic polyether urethane material.
 8. The catheter apparatus of claim 7 wherein the flexible curved tip is composed of about 5 to 30 weight percent of siloxane blended with the thermoplastic polyether urethane material.
 9. The catheter apparatus of claim 1 wherein, in the deployed configuration, the energy delivery elements carried by the support structure are spaced apart from each other along a longitudinal axis of the renal artery and are configured to maintain apposition with a wall of the renal artery.
 10. The catheter apparatus of claim 1 wherein the energy delivery elements comprise a series of band electrodes.
 11. The catheter apparatus of claim 10 wherein at least one of the band electrodes comprises tapered end portions, and wherein the tapered end portions are configured to provide an obtuse angle between an outer surface of the support structure and an outer surface of the at least one band electrode.
 12. The catheter apparatus of claim 1 wherein the therapeutic assembly comprises four energy delivery elements.
 13. The catheter apparatus of claim 1, further comprising a retractable loading tool surrounding and restraining at least a longitudinal portion of the therapeutic assembly in the low-profile delivery configuration.
 14. The catheter apparatus of claim 13 wherein the loading tool comprises a distal end portion having rounded edges.
 15. A renal neuromodulation system for treatment of a human patient, the system comprising: an elongate shaft having a proximal end and a distal end, wherein the distal end of the shaft is configured for intravascular delivery over a procedural guide wire to a renal artery of the patient; a pre-shaped tubular spiral structure disposed at or proximate to the distal end of the elongate shaft, wherein the spiral structure is configured to transform between an unexpanded configuration and an expanded configuration that tends to assume the shape of the pre-shaped spiral structure, and wherein the spiral structure is composed, at least in part, of multifilar stranded nitinol wire; and a plurality of electrodes associated with the spiral structure, wherein the elongate shaft and the spiral structure together define a guide wire lumen therethrough, and wherein the guide wire lumen is configured to slidably receive the procedural guide wire to locate the spiral structure at a target treatment site within a renal blood vessel of the patient and to restrain the spiral structure in the unexpanded configuration, and wherein proximal movement of the procedural guide wire through the guide wire lumen relative to the spiral structure such that a distal end portion of the guide wire is at least partially within the guide wire lumen transforms the spiral structure to the expanded configuration.
 16. The system of claim 15 wherein the procedural guide wire comprises a distal portion having varying flexibility therealong, and further wherein at least a region of the distal portion of the guide wire is configured to remain within the portion of the guide wire lumen defined by the spiral structure when the spiral structure is in the expanded configuration.
 17. The system of claim 15, further comprising a flexible tube covering and in intimate contact with the spiral structure.
 18. The system of claim 17 wherein the plurality of electrodes are bonded to the flexible tube using an adhesive material.
 19. The system of claim 15 wherein the plurality of electrodes are composed of gold.
 20. The system of claim 15 wherein the plurality of electrodes are individually connectable to an energy source external to the patient, and wherein the energy source is capable of individually controlling the energy delivered to each electrode during therapy. 